Lens module with filter element

ABSTRACT

A lens module includes a lens barrel, at least one lens, and a filter element. The lens barrel includes an object-side end and an image-side end opposite to the object-side end. The at least one lens is received in the lens barrel. The filter element is received in the lens barrel, and includes a transparent substrate, an anti-reflection film, and an infrared filtering film. The transparent substrate includes an object-side surface facing the object-side end and an image-side surface facing the image-side end. The anti-reflection film is coated on the object-side surface, and the infrared filtering film is coated on the image-side surface.

BACKGROUND

1. Technical Field

The present disclosure relates to lens modules and, particularly, to a lens module with a filter element.

2. Description of Related Art

Lens modules include at least one lens and a filter element generally positioned at an image side of the lens. The filter element includes a transparent substrate and an infrared filtering film coated on an object side of the transparent substrate. The filter element is for filtering infrared light rays while transmitting visible light rays. However, current filter elements cannot transmit 100% visible light rays and reflect a minority of visible light rays, more than about 5%, which form a glare in an image after multiple reflections.

Therefore, it is desirable to provide a lens module, which can overcome the limitations described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view of a lens module of an exemplary embodiment.

FIG. 2 is a spectrum chart of an infrared filtering film of a filter element of the lens module of FIG. 1.

FIG. 3 is a spectrum chart of an anti-reflection film of a filter element of the lens module of FIG. 1.

DETAILED DESCRIPTION

Embodiments of the disclosure will now be described in detail, with reference to the accompanying drawings.

FIG. 1, shows a lens module 100, according to an exemplary embodiment. The lens module 100 includes a lens barrel 10, at least one lens 20, a filter element 30, and an image sensor 40.

The lens barrel 10 is tubular and includes an object-side end 11 and an image-side end 12 opposite to the object-side end 11. The lens barrel 10 defines a receiving room 13 extending through the object-side end 11 and the image-side end 12. In this embodiment, the lens barrel 10 is made of light-shielding/opaque/black material(s).

The at least one lens 20 is received in the receiving room 13, adjacent to the object-side end 11. Each of the at least one lens 20 is made of plastic, glass, or other transparent materials, and is spherical or aspherical. In this embodiment, the lens module 100 includes two lenses 20 arranged in the receiving room 13 from the object-side end 11 to the image side end 12.

The filter element 30 is received in the receiving room 13, adjacent to the image side end 12. The filter element 30 includes a transparent substrate 31, an anti-reflection film 32, and an infrared filtering film 33. The transparent substrate 31 includes an object-side surface 311 facing the object-side end 11 and an image-side surface 312 facing the image-side end 12. The anti-reflection film 32 is coated on the object-side surface 311, and the infrared filtering film 33 is coated on the image-side surface 312.

In this embodiment, the transparent substrate 31 is made of glass, and a thickness of transparent substrate 31 is from about 0.2 mm to about 0.8 mm. A little of copper oxide (CuO) is doped in the materials of making the transparent substrate 31 for absorbing a part of infrared light rays. The anti-reflection film 32 includes first to fourth layers orderly stacked on the image-side surface 311. The odd numbered layers of the anti-reflection film 32 are made from titanium dioxide (TiO₂) and the even numbered layers of the anti-reflection film 32 are made from silicon dioxide (SiO₂). The material and thickness of each layer of the anti-reflection film 32 are shown in Table 1.

TABLE 1 Layers Material Thickness (nm) First layer TiO₂ 11.52 Second layer SiO₂ 28.93 Third layer TiO₂ 111.15 Fourth layer SiO₂ 83.78

The infrared filtering film 33 includes first to fifty fourth layers orderly stacked on the object-side surface 312. The odd numbered layers of the infrared filtering film 33 are made from TiO₂, and the even numbered layers of the infrared filtering film 33 are made from SiO₂. The material and thickness of each layer of the infrared filtering film 33 are shown in Table 2.

TABLE 2 Layers Material Thickness (nm) First layer TiO₂ 7.28 Second layer SiO₂ 18.67 Third layer TiO₂ 86.78 Fourth layer SiO₂ 142.53 Fifth layer TiO₂ 80.33 Sixth layer SiO₂ 132.59 Seventh layer TiO₂ 81.28 Eighth layer SiO₂ 128.33 Ninth layer TiO₂ 81.96 Tenth layer SiO₂ 124.34 Eleventh layer TiO₂ 83.38 Twelfth layer SiO₂ 121.71 Thirteenth layer TiO₂ 83.92 Fourteenth layer SiO₂ 123.09 Fifteenth layer TiO₂ 84.08 Sixteenth layer SiO₂ 124.78 Seventeenth layer TiO₂ 84.81 Eighteenth layer SiO₂ 134.73 Nineteenth layer TiO₂ 97.58 Twentieth layer SiO₂ 192.39 Twenty first layer TiO₂ 104.2 Twenty second layer SiO₂ 148.59 Twenty third layer TiO₂ 83.66 Twenty fourth layer SiO₂ 143.14 Twenty fifth layer TiO₂ 93.6 Twenty sixth layer SiO₂ 177.52 Twenty seventh layer TiO₂ 105.92 Twenty eighth layer SiO₂ 158.12 Twenty ninth layer TiO₂ 87.79 Thirtieth layer SiO₂ 152.72 Thirty first layer TiO₂ 96.32 Thirty second layer SiO₂ 174.89 Thirty third layer TiO₂ 104.29 Thirty fourth layer SiO₂ 163.45 Thirty fifth layer TiO₂ 100.46 Thirty sixth layer SiO₂ 180.21 Thirty seventh layer TiO₂ 115.65 Thirty eighth layer SiO₂ 188.01 Thirty ninth layer TiO₂ 117.25 Fortieth layer SiO₂ 191.74 Forty first layer TiO₂ 118.28 Forty second layer SiO₂ 192.04 Forty third layer TiO₂ 116.57 Forty fourth layer SiO₂ 192.79 Forty fifth layer TiO₂ 117.32 Forty sixth layer SiO₂ 190.86 Forty seventh layer TiO₂ 118.16 Forty eighth layer SiO₂ 190.44 Forty ninth layer TiO₂ 116.69 Fiftieth layer SiO₂ 191.4 Fifty first layer TiO₂ 114.71 Fifty second layer SiO₂ 186.74 Fifty third layer TiO₂ 113.18 Fifty fourth layer SiO₂ 92.44

The anti-reflection film 32 can be stacked by any number of layers with other materials for anti-reflecting light rays. The infrared filtering film 33 can be stacked by any number of layers with other materials for filtering infrared light rays.

The image sensor 40 is positioned at the image-side end 12 for covering the receiving room 13. The light rays penetrating the at least one lens 20 and the filter element 30 are projected on an imaging surface of the image sensor 40 for converting the light rays to electrical signals.

Referring to FIGS. 2-3, in use, light rays enter into the lens module 100 from the object-side end 11 of the lens barrel 10 and strike the filter element 30. The light rays orderly penetrate the anti-reflection film 32, the transparent substrate 31, and the infrared filtering film 33. The infrared light rays of the light rays penetrating the anti-reflection film 32 are filtered by the infrared filtering film 33. As the anti-reflection film 32 enhances transmissivity of the light rays projected on the filter element 30, the light rays reflected by the anti-reflection film 32 are less than about 5%. Therefore, the light rays can form reducing a glare in an image, and the quality of the image is enhanced.

Particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure. 

1. A lens module, comprising: a lens barrel comprising an object-side end and an image-side end opposite to the object-side end; at least one lens received in the lens barrel; and a filter element received in the lens barrel, and comprising a transparent substrate, an anti-reflection film, and an infrared filtering film; the transparent substrate comprising an object-side surface facing the object-side end and an image-side surface facing the image-side end; the anti-reflection film coated on the object-side surface, and the infrared filtering film coated on the image-side surface.
 2. The lens module of claim 1, wherein the anti-reflection film is configured for enhancing transmissivity of light rays projected thereon, and the infrared filtering film is configured for filtering infrared light rays.
 3. The lens module of claim 2, further comprising an image sensor positioned at the image-side end, wherein the filter element is positioned between the least one lens and the image sensor.
 4. The lens module of claim 3, wherein the anti-reflection film faces the at least one lens, and the infrared filtering film faces the image sensor.
 5. The lens module of claim 1, wherein the anti-reflection film comprises first to fourth layers orderly stacked on the image-side surface, the odd numbered layers of the anti-reflection film are made from titanium dioxide (TiO₂), and the even numbered layers of the anti-reflection film are made from silicon dioxide (SiO₂).
 6. The lens module of claim 1, wherein the infrared filtering film comprises first to fifty fourth layers orderly stacked on the object-side surface, the odd numbered layers of the infrared filtering film are made from TiO₂, and the even numbered layers of the infrared filtering film are made from SiO₂.
 7. The lens module of claim 1, wherein the transparent substrate is made of glass, and a thickness of the transparent substrate is from about 0.2 mm to about 0.8 mm. 